Gypsum and Row Spacing Questions
Last week I met with a grower who has a farming operation in Scotland Co., NC. and wants to start growing peanuts. He currently uses gypsum on all of his land regardless of the crop. One of the questions he had was about timing of the gypsum application for peanuts. Apparently the gypsum he is applying now is broadcast prior to planting. I remember that some growers have tried putting it out on peanuts pre plant but this must not work as everyone I know puts it out at blooming. What are your thoughts?
Research from many years ago demonstrated that gypsum applications at planting do not perform as consistently as applications just prior to pegging. It is essential to have a relatively high concentration of calcium in the pegging zone as peanuts begin to flower and produce pegs. This can last for 2 months due to the indeterminate nature of peanuts. Applying gypsum as a pre treatment at planting can result in significant leaching of calcium out of the pegging zone. Also, and this is especially true for conventional tillage on beds, when we get rain showers, especially if they are intense, the soil on the bed washes to the furrow and along with that soil is the calcium. Best results with the least amount of risk are to let the peanuts get 12-16 inches in diameter prior to application. Many growers do this earlier when peanuts are smaller and in most years they are probably fine. But, when we get heavy rains in early and mid-June when the peanuts are relatively small there is always the question of how much gypsum was lost and should someone apply more. Because we cannot rely on soil sampling (soil calcium is not a good indicator of Virginia market type response to gypsum) this becomes guess work. On page 24 of the 2015 Peanut Information book we address this situation but there is a lot of guessing in that. But PRE application of gypsum would increase risk even greater than the scenario mentioned in the production guide.
Another issue is row spacing. Currently he plants everything on 30″ row spacing. I know there are producers in the SE that plant runners on 30″ rows but I can see issues with this on Virginias. Can you address this for us?
We have a few growers in North Carolina who have shifted to 30 inch rows and they have well as far as I know. They did this so they could match up equipment for other crops. The challenge is planting on beds. One that I am aware from years ago in Perquimans County may have prepared beds but another grower in Sampson county plants flat. I think it is even more important that they have a GPS guidance system for digging if planting in 30 inch rows in flat seedbeds. Apogee can help but I do worry some about applying on 30 inch rows because the peanuts lap before they are as far along in the reproductive development phase as peanuts would be on 36 or 38 inch rows. I don’t know that this matters. The farmer in Sampson county had big increases in yield with Apogee when growing on 30 inch rows in 2014. In 2015 in the same kind of trial I think his yields might be lower after Apogee in 30 inch rows; I have not run those data for 2015.
All this to say 30 inch rows are okay. In the SE they often plant flat and they have some rather unique patterns that are not the tradition 36-38 plantings on beds. Whatever he does he needs to be able to track the rows for digging and that can be more of a challenge in narrower spacings. For Virginia types I always recommend beds, and single or twin 36-38 rows enables a person to do this. When you get narrower than this you are limited. From a yield standpoint, it will be hard to beat twin rows on 36-38-inch spacings. That seems to be optimum. We did work with what I called a “narrower twin row pattern” years ago (having an extra set of twins between regular twins) and the yields were the same as the normal twin row pattern.
But to match equipment, the 30 inch rows should be fine.
Hope this helps.
Article first appeared as North Carolina Peanut Note (PNNC-2015-175)